UV
‐Induced Degradation and Active Restructuring of
LSR
Mold Surfaces: Restoring Release Functionality Through
LMW PDMS
Wonsun Lee, Kiyoung Kim ABSTRACT
This study investigates the loss and restoration of release functionality in service‐aged liquid silicone rubber (LSR) molds used for UV‐curable epoxy injection. Repeated molding cycles and UV exposure were associated with epoxy‐residue accumulation and surface oxidation, which reduced surface hydrophobicity and promoted demolding failure. Conventional water‐based cleaning removed loosely bound contaminants and gave only temporary wetting recovery, indicating that cleaning alone did not restore the degraded surface chemistry. We therefore developed a regeneration protocol combining ultrasonic cleaning with baking at 140°C. X‐ray photoelectron spectroscopy (XPS) and attenuated‐total‐reflectance Fourier‐transform infrared spectroscopy (ATR‐FTIR) showed a decrease in silanol‐related signals and recovery of the siloxane‐rich surface after the combined treatment, consistent with outward migration of low‐molecular‐weight polydimethylsiloxane (LMW PDMS). The regenerated molds retained dimensional stability and achieved a > 44% increase in functional lifetime in a pilot‐scale UV‐epoxy injection process. These findings provide a practical regeneration route for extending the service life of LSR molds while clarifying the coupled roles of contaminant removal and thermally activated surface restructuring.